Hydraulic hoist for dumping trucks



Dec. 20, 1932. A. E. KNECHT HYDRAULIC HOIST FOR DUMPING TRUCKS Filed Jan. 21, 1932 2 Sheets-Sheet flrZ/zzu 15'. Karach Dec. 20, 1932.

A. E. KNECHT HYDRAULIC HOIST FOR DUMPING TRUCKS Filed Jan. 21, 1952 2 Sheets-Sheet 2 yaw/@1- 15'. Raga/w.

and violent contact between the body Patented Dec. 20, 1 932 uNiTEasTA ras names a. 1mm, or canon; omo," assmnoa 'r'o' rimjrnnrnorion isrnnr. Bonv' or canon. 0x10, 4 coaronarron or onro I mmmorromr iron nunrmo 'raudxs' ime filed-January a1, 1932. semino. $87,993:

This invention relates to hydraulic hoists for dumping body trucks and has for its object the provision of means whereby the descent of the dumping body wilLbe-checked and the chassis will be avoided. Another object of the invention is to so arrange the connections between the dumping body and the operat- "or'cables Q'fitted tothe arcuatejedges of seg-.

ments 10 and secured to said segments .so that, when the piston and" crosshead move foring piston that the lifting force will be most effectually applied and heavy loads may be easily raised to the dumping position. The invention is illustrated in the accom anying drawings and will be hereinafter ully set forth and defined. p

In the drawings, Fig. 1 is a side elevation, partly in section, of a hoisting mechanism embodying the present invention,

' Fig. 2 is a. plan view on a somewhat larger scale with parts in section,

Fig. 3 is amenlarged detail section on the line 3 v3,0f'

of'the vehicle may be of any suitable" construction and is designated generally by the reference numeral 1,' the dumping body, indicated at 2, being fulcrumed at the rear end of the chassis, as shown at 3, so

. ported on the chassis, upon the m ial longitudinal line thereof, is a cylinder 4 in which is fitted a piston 5 to which, is secured a piston rod 6 which projects forwardly through the front head of the cylinder and has a crosshead 7 firmly secured to its front end. The crosshead projects to the opposite sides of the cylinder and to the ends of the crosshead are secured the front ends of connecting .rods 8 to the rear ends of which are attached chains wardly, the segments will be rocked. The seg ments are rigidly secured to or formed integral with the inner ends of hollow rock shafts 11 which are mounted upon the ful crum or pivot rod 12 which is secured rigidly upon andv extends transversely of the chassis, as will be understood. At the outer ends of underside of the dumping body. It will now ing part-s.

ends of lifting links l l which extend upwardly and have their upper ends pivoted to the be understood that if force be applied to the piston 5, to move the same forwardly, the

. crosshead 7 will be also moved forwardly and will transmit a pull through the connecting rods 8 to the chains or. cables 9 and thereby effect a rocking of the segments 10. The movement of the segments 10 will be transmitted directly to the rock shafts 11 and, as a result, the cranks or levers 13 will be rocked u wardly so that a lifting force will be ap' pied through the links 14 to the dumping ody to raise it to the dumping position.

When the load is discharged, the piston may be relieved of the actuating force whereupon "I5 the weight of the body will cause itto descend and impart reverse movement to the several connected parts so that the piston will be returnd toward the rear end of the cylinder and the-apparatus will be set for a second operation. By disposing the crank arms in a forwardly extendin relation to the rock shafts, the liftin' lin s will be arranged so as to most efi'ectua 1y apply the lifting force inasmuch as they form the most advantageous angle with the dumping body in the various positions thereof as it rises and the mecha nism is very compact and simple so that the hoisting operation may be very easily performed with minimum strain upon the work Thefpistom 5 is moved? forwardly by the action of oil orothe'r non-compressible fluid driven against the piston by the action of a gear pump mounted uponthe chassis, this gear pump being illustrated conventionally at 15 and being of well-known construction. The pump is connected with the forward end of the cylinder 4 through a pipe 16 which communicates with the cylinder through the bottom thereof, near its forward end, and another pipe 17 leads from the pump to the rear end of the cylinder so as to communicate with the interior of the cylinder at the rear of the piston. A controlling valve, indicated at 18, is provided in the pump to govern the circulation .of the oil therethrough and determine the direction of the flow according to the po sition of the valve. A hand lever 19 is mounted upon the truck, within the chauffeurs cabin, or at some point within convenient reach of the chauffeur, and is connected through a connecting rod 20 and a lever and link mechanism 21 with the valve so as to set the same in any desired position. Thepump is driven through a shaft 22 connected with a power take-o'fi 23 mounted on the truck and forming a portion of its ower plant, a hand lever 24 being provi ed to throw the power take-01f into or out of action as may be needed. The cylinder, the pipes 16 and 17 and the working chambers of the ump are filled with the non-compressible fluid and it will be understood that the forward portion of the cylinder constitutes a reservoir for the inert fluid and when the pump is set in operation the fiuid is drawn from the reservoir and forced around to the rear end or power chamber of the cylinder to drive the piston forwardl If the pump be reversed by properly settlng the controlling valve, the circulation of the fluid will then be from the rear end of the cylinder, back to the front end or reservoir, so that the piston will be driven rearwardly, and the dumping body is ob viously raised u on the forward movement of the piston an lowered upon the rearward movement thereof.

The dumping bodies are quite heavy, even when unloaded, and may be lowered by the force of gravity if the pump be set in neutral position. Frequently, heretofore, the dumping bodies have descended so rapidly that they impinged upon the chassis and parts mounted thereon with such force as to greatly damage the parts and frequently renered them inoperative. It is a particular object of my present invention to provide means whereby this rapid dama 'ng descent of the body will be prevented. 'I d this end, I extend the rear end of the piston rod 6 rearwardly through the piston and form therewith or firmly secure thereto a stem 25 which pro jects rearwardly and is provided with a head 26 at its rear end. A nut 27 fitted on the reduced rear end of the'piston rod, isturned .shown clearly in Fig. 3, so that home against the rear side of the piston, as t e piston other circulating fluid to enter the rear end of the piston through the rear head. This valve is in the form of a disk having its rear end preferably beveled so as to easily seat itself, and an expansion spring 31 is fit ted about the stem, between the nut 27'and the valve, and tends constantl to move the valve toward the rear end of t e stem. The valve is provided with small passages 32 therethrough, parallel with its axis and so disposed as to communicate with the opening 30 when the valve is seated, as shown in Fig. 3. When the oil is being circulated so as to enter the rear end of the cylinder, the pressure applied to the oil will overcome the force of the spring 31 and unseat the valve so that the oil will act upon the piston and drive the same forward to effect raisin of the dump body. The spring 31 will, however, resist the unseating of the valve momentarily so that the movement of the piston will be started without any jerking which imparts unnecessary strain to the working parts. As the piston moves forwardly, and the valve is unseated under the pressure exerted thereon, the spring expands and moves the valve relatively rearward upon the stem 25, this movement being limited by the head 26 in an obvious manner so that the valve cannot be lost. When the body is being lowered and the piston is moving rearwardly, the movement may be somewhat rapid until the valve is brought to its seat whereupon the passage of the oil from the rear end of the cylinder .will be checked inasmuch as the area through which it may ass will be reduced to the combined areas 0 the small passages 32 so that the outflow will be very greatly restricted and, con

sequently, the rearward movement of the piston will be pronouncedly checked and the final downward movement of the body will be very slow so that it cannot forcibly impinge upon the chassis or any of the parts mounted thereon. The apparatus embod ing my present improvements is exceeding y simple and compact and its many advantages are thought to be obvious.

Having thus described the invention, I claim:

1. A hydraulic hoisting mechanism for dumping trucks comprising a cylinder forming a part of a closed fluld-circulating system, a piston in the cylinder means for supplying a non-compressible fiuid to the cy inder at the rear of the piston and Withdrawing said fluid form the cylinder at the front of the piston to impart movement to the piston, a stem extending axially from the piston, a valve slidably mounted upon said stem, means to limit the movement of the valve on the stem, and yieldable means for holding said valve toward the end of the stem, the valve being adapted to seat in' the end of the cylinder and constructed to permita retarded flow when seated.

2. In a hydraulic hoistin mechanism for dumping trucks, a cylinder aving a port in its rear end, said cylinder forming a part of a closed circulating system filled with a" noncompressible fluid, a piston movable in the cylinder, the fluid in the circulating system being admissible through the port in the end of the cylinder whereby to effect movement of the piston in the cylinder, a stem extended axially rearwardly from the piston and fixed thereto and adapted to pass through the port in the end 0 the cylinder, :1 disk valve mounted on said stem and adapted to seat in said port and having minute passages therethrough, a head at the rear end of the stem to limit the movement of the valve rearwardly, and an expansion spring between the piston and said valve acting on the valve to hold it toward said head.

In testimony whereof I affix my. signature.

ARTHURE. KNECHT. [11. a] 

